Too be honest though the due date isn't just for the student; it gives the teacher a schedule on when to grade it. If people start handing things in early it probably gets stressful, especially when the teacher is under a strict schedule of grading papers as new ones are coming in.

As a college student this is why I love the option to turn your work in early, but most importantly ONLINE :-) . But even more so, why I love Rate My Professor. I like to see if a teacher is unorganized before I choose their class. Most students are flat out honest and will give you the real deal on a professor.
I hope it gets better for you OP. Maybe next time you should consider printing out an extra copy in case something like this happens again. Teachers are human too.

Id take it up with the principle, was it a typed one? You can always reprint it at least if it was and screen shot time it was saved...
Sorry about that tho :( hope it all works out in your favor in the end OP.

Definitely not a fault on your part, OP. I remember when I faced a similar teacher. If she won't listen to reason I would say just play it along, as they often think "Oh, you didn't spend enough time working on it."
Good luck anyway!